Commits
Matt Fleming committed 47997d756aa
x86/rtc: Don't recursively acquire rtc_lock
A deadlock was introduced on x86 in commit ef68c8f87ed1 ("x86:
Serialize EFI time accesses on rtc_lock") because efi_get_time()
and friends can be called with rtc_lock already held by
read_persistent_time(), e.g.:
timekeeping_init()
read_persistent_clock() <-- acquire rtc_lock
efi_get_time()
phys_efi_get_time() <-- acquire rtc_lock <DEADLOCK>
To fix this let's push the locking down into the get_wallclock()
and set_wallclock() implementations. Only the clock
implementations that access the x86 RTC directly need to acquire
rtc_lock, so it makes sense to push the locking down into the
rtc, vrtc and efi code.
The virtualization implementations don't require rtc_lock to be
held because they provide their own serialization.
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Acked-by: Jan Beulich <jbeulich@novell.com>
Acked-by: Avi Kivity <avi@redhat.com> [for the virtualization aspect]
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Josh Boyer <jwboyer@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>